Prion protein (PrP) contains two
N-linked glycosylation sites. It is unknown which amino acid substitution contributes most efficiently to the abolishment of
N-linked glycosylations. To define the ...influence of amino acid substitution at the
N-linked glycosylation sites on the conversion efficiency of mouse PrP, we tested each of all 19 amino acid substitutions at either one of the
N-linked glycosylation sites (codon 180, 182, 196 or 198). The conversion efficiency of the mutagenized PrP was highly dependent on the newly introduced amino acid itself regardless of the absence of
N-linked glycosylation in scrapie-infected mouse neuroblastoma cells. The majority of mutant PrP with substitutions at the Asn residues of the
N-linked glycosylation sites were conversion-competent, whereas most mutant PrP with substitutions at the Thr residues were conversion-incompetent. These findings emphasize that the Asn residues of the
N-linked glycosylation sites are replaceable to abolish
N-linked glycosylations without directly affecting the protein function.
We report here a 75-year-old-male with a slowly progressive dementia of 5-year duration along with a rapid exacerbation of symptoms in the terminal 3 months. Neuropathological examinations revealed ...findings consistent with conspicuous Alzheimer's disease and mild Creutzfeldt-Jakob disease (CJD). The plaque amyloid was exclusively composed of beta-protein. The immunohistochemistry of prion protein using hydrolytic autoclaving pretreatment showed diffuse gray matter stainings in the sections of both the cerebral and cerebellar cortices. This method was thus considered useful in confirming the diagnosis of CJD for this case.
Using 7.4 kb of 5′ flanking DNA from the
Drosophila cholinergic gene locus to drive Gal4 expression we can visualize essentially all cholinergic neurons and neuropiles after genetic recombination ...with a UAS–GFP (S65T) reporter gene. In contrast to previous methods somata and neuropiles can be observed in the same samples. Fluorescence intensity is strong enough to allow observations in live animals at all developmental stages. Three-dimensional reconstructions made from confocal sections of whole-mount preparations reveal the extensive cholinergic connections among various regions of the nervous system.
Abnormal accumulation of Aβ and tau in senile plaques (SP) and neurofibrillary tangles (NFTs) is a key event in Alzheimer’s disease (AD). Here, we show that T668-phosphorylated cytoplasmic domain of ...APP (pT668-ACD) accumulates Aβ and tau in AD and its transgenic models. Anti-pT668 immunostaining of AD brain sections with hydrated autoclave enhancement identified SP neurites and NFTs in which pT668-ACD colocalizes with tau. We produced and examined transgenic (Tg) mice that overexpress human APP695, harboring the double Swedish/London mutation, and develop age-dependently Aβ plaques in the brain. All Aβ plaques contain co-accumulations of pT668-ACD, but co-accumulation of tau appears in only a fraction of Aβ plaques in older animals. We also examined the established tau Tg mice that overexpress the smallest human brain tau isoform and develop neuronal accumulations of tau in older animals. Examination of the old tau Tg mice showed that neuronal cells affected by tau accumulation induce co-accumulation of pT668-ACD. We speculate that in AD brains, extracellular Aβ deposition is accompanied by intracellular accumulation of pT668-ACD, followed by tau accumulation in the SP with dystrophic neurites and that neuronal cells affected by tau accumulation induce co-accumulation of pT668-ACD in NFTs. Thus, pT668-ACD is likely to mediate pathological interaction between Aβ and tau.
We examined 7 patients with Creutzfeldt-Jakob disease (CJD) with a methionine-to-valine change at prion protein (PrP) codon 129 (CJD129 patients). These CJD129 patients did not have either a codon ...117 or 198 point mutation. For comparison, we also examined 7 patients with Gerstmann-Sträussler syndrome (GSS) with a proline-to-leucine change at PrP codon 102 (GSS102 patients) and 13 patients without any known mutations at codons 102, 117, 129, 178, or 200 (CJDwild patients). CJD129 patients had a long clinical duration and ataxia at onset, but rarely had any periodic synchronous discharge in their electroencephalogram. Unlike CJDwild patients, all CJD129 patients have typical congophilic PrP plaques in their brain. These clinicopathological findings were similar to those of GSS102. However, the distribution and morphology of PrP deposits revealed by immunohistochemistry were different between CJD129 and GSS102. In GSS102 more numerous and various types of PrP plaques are seen throughout the brain, while in CJD129 patients a unicentric core was the major feature of PrP plaques. The change in codon 129 influences the clinical course and pathological findings in CJD.
The protease resistant isoform of prion protein (PrP) is a diagnostic marker of spongiform encephalopathies in humans and animals. Immunoblotting is a sensitive method but requires either fresh or ...frozen, unfixed materials. Immunohistochemistry using formalin-fixed, paraffin-embedded materials is now also considered to be sensitive and comparable to immunoblotting after various treatments, especially using the hydrolytic autoclaving method on tissue sections before staining. The advantage of this method is that it can be applied to routine pathology materials or long preserved materials. The kuru plaque-type deposition of PrP suggests abnormalities of the PrP gene, while synaptic-type deposition suggests either sporadic CJD or particular familial CJD. PrP gene abnormalities are thus related to PrP deposition and modify clinical symptoms and their progression. A PrP gene analysis can be done using either preclinical, clinical or post-mortem materials.
To elucidate the association between medical procedures and sporadic Creutzfeldt-Jakob disease (sCJD), we analyzed medical procedures (any surgical procedure, neurosurgery, ophthalmic surgery, and ...blood transfusion) for patients registered by the CJD Surveillance Committee in Japan during 1999-2008. We conducted an age-stratified case-control study with 753 sCJD patients and 210 controls and a study of patients who underwent neurosurgical or ophthalmic surgical procedures at the same hospital. Although the control group was relatively small, no evidence was found that prion disease was transmitted through the investigated medical procedures before onset of sCJD. After onset of sCJD, 4.5% of the sCJD patients underwent operations, including neurosurgical for 0.8% and ophthalmic for 1.9%; no special precautions against transmission of prion diseases were taken. Fortunately, we have not identified patients with prion disease attributed to these operations. Our findings indicate that surgical procedures or blood transfusion had little effect on the incidence of sCJD.
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